In general, compressors are devices for compressing fluid such as refrigerant gas and the like, and may be classified into a rotary compressor, a reciprocal compressor, a scroll compressor and the like according to a method of compressing the fluid.
The scroll compressor is a high-efficiency and low-noise compressor which is widely applied to an air-conditioning field. The scroll compressor operates in the following manner. That is, while two scrolls respectively having a fixed wrap and an orbiting wrap orbit relatively, a plurality of compression chambers are formed as a pair between the fixed wrap and the orbiting wrap of each scroll. As their volumes of the compression chambers decrease while they continuously move toward their center, a refrigerant is continuously sucked, compressed and discharged.
Behaviors of the scroll compressor may depend on shapes of the fixed wrap and the orbiting wrap. Although they can have a random shape, the fixed wrap and the orbiting wrap typically have a shape of an involute curve which is easy to be processed. The involute curve refers to a curve corresponding to a track drawn by an end of a string, which is wrapped around a base circle having a random radius, when the string is unwound. Upon the use of the involute curve, wraps have a uniform thickness and accordingly a coefficient of volume change is constant. Therefore, in order to obtain a satisfactory compression ratio, the number of turns of the wrap has to increase. However, it also causes the compressor to increase in size.
FIG. 1 is a sectional view showing a structure of a horizontal type scroll compressor according to the related art.
As shown in FIG. 1, a scroll compressor according to the related art includes a main frame 2 and a sub frame 3 disposed within an inner space 11 of a casing 1 in a horizontal direction with a predetermined interval, a driving motor 4 installed between the main frame 2 and the sub frame 3 to generate a rotational force, and a crankshaft 5 formed in a center of a rotor 42 of the driving motor 4 and penetrating through the main frame 2 to be coupled to the orbiting scroll 7 so as to transfer the rotational force of the driving motor 4 thereto.
A fixed scroll 6 is fixed to a front of the main frame 2, and an orbiting scroll 7 is engaged with the fixed scroll 6 to form two compression chambers S as a pair which move continuously. An Oldham's ring 8 is installed between the orbiting scroll 7 and the main frame 2 such that the orbiting scroll 7 can orbit without rotation.
A shaft receiving hole 21 for supporting the crankshaft 5 in a radial direction is formed in the central portion of the main frame 2, and a main bearing 22 for supporting the crankshaft 5 in a radial direction is installed in the shaft receiving hole 21.
A fixed wrap 62 forming the pair of compression chambers S is formed in an involute shape on a rear surface of a fixed disk 61 of the fixed scroll 6. A suction port (not shown) is formed at a side surface of the fixed disk 61 to be directly connected to a suction pipe 13 such that a refrigerant can be sucked into the compression chambers S. A discharge port 63 is formed at a center of a front surface of the fixed disk 61 such that a refrigerant gas compressed in the compression chambers S can be discharged into the inner space 11 of the casing 1. A discharge valve 9 for opening or closing the discharge port 63 to prevent the refrigerant gas from flowing backwardly is disposed at a front surface of the fixed scroll 6.
An orbiting wrap 72 which forms two compression chambers S as a pair together with the fixed wrap 62 of the fixed scroll 6 is formed in an involute shape on a front surface of an orbiting disk 71 of the orbiting scroll 7. A boss portion 73 is formed at a center of a rear surface of the orbiting disk 61. The boss portion 73 is coupled to the crankshaft 5 to transfer the rotational force from the driving motor 4 to the crankshaft 5. A pin bearing 74 for support between the crankshaft 5 and the boss portion 73 in a radial direction is installed on an inner circumferential surface of the boss portion 73.
An unexplained reference numeral 12 denotes an inlet, 13 denotes an outlet, 31 denotes a sub bearing for supporting the crankshaft 4 in a radial direction, 41 denotes a stator of the driving motor 4, and 51 denotes an oil passage.
Hereinafter, description will be given of an operation of the related art scroll compressor.
That is, when power is applied to the driving motor 4, the crankshaft 5 rotates together with a rotor 42 of the driving motor 4. Accordingly, the orbiting scroll 7 orbits on an upper surface of the main frame 2 by the Oldham's ring 8 as far as an eccentric distance, and simultaneously, two, namely, a pair of compression chambers S are continuously formed between the fixed wrap 62 and the orbiting wrap 72. As the compression chambers move, with their volumes decreased, toward their center in response to a continuous orbiting motion of the orbiting scroll 7, a refrigerant gas is continuously, sucked, compressed and discharged.